Neutron Definition and 746 Threads

Hello! I have a very interesting question, whose answer I have not yet been able to find out. Now, according to The Standard Model there are three generations of matter, therefore three generations of quarks also. Generations of Quarks: 1st: up (u) & down (d) 2nd: charming (c) &...

I had a homework question I am really stuck on- How do you calculate neuron flux

A neutron collides elastically with a helium nucleus (at rest initially) whose mass is four times that of the neutron. The helium nucleus is observed to move off at an angle θ'2 = 45° from the neutron's initial direction. The neutron's initial speed is 7.0 × 105 m/s. a) Determine the angle of...

Homework Statement Supposed that the mass of certain spherical neutron star is twice the mass of the sun (1.991*10^30) and its radius is 13.5 km. Determine the greatest possible angular speed it can have so that the matter at the surface of the star on its equator is just held in orbit by...

1. A neutron has a kinetic energy of 10MeV. What size object is necessary to observe neutron diffraction effects? Is there anything in nature of this size that could serve as a target to demonstrate the wave number of 10MeV neutrons? K= 10MeV or 1.602 x 10^-12J Mass of neutron = 1.675...

This question concerns a problem in Arfken and Weber (from the infinite series chapter, after the power series section). I went to the homework section, and the titles beneath each section specifically imply that a question from a graduate book is inappropriate for that section. I thus post it...

Calculate the velocity and kinetic energy of a neutron (mass 1.675x10-27kg) that has a wavelength of 0.2nm. How does this compare to the average kinetic energy of a gas molecule at room temperature (0.038eV at 200C)? 1. E=mc^2 2. KE = 1/2 mv^2 I used 1. to calculate the energy which was...

Does anyone know anywhere where I can find reliable up-to-date cross section infromation? In particular I'm looking for the absorption cross section of Gadolinium-157 for thermal neutrons. Everywhere I look seems to give a different value ranging fro 70000barns up to 450000barns.

I know there is no way to deflect a neutron by electromagnetic force since it is a uncharged particle.Can anyone come up with any other ways?Thanks very much.

how to turn a proton into neutron by e+p-->n? Just as the topic said,is it possible to turn a proton into a neutron by forcing a electron into the proton?If it's possible,what condition is it required?

Homework Statement Calculate the binding energy of a neutron in 13-C. Homework Equations mass defect= (Z*mp) + (N*mn) - (mc13) B = mass defect * conversion factor B/(Z+N) = Binding Energy per Neutron I wasn't given any values for the numbers, so I wiki'd them. The Attempt at a...

This question is probably very basic for those who understand nuclear fusion but it has been annoying me for a while now and I would like an answer. I have tried searching these forums but I can't find what I'm looking for. The sun is constantly fusing hydrogen atoms to form helium atoms...

A neutron star cannot spin with less than a certain critical period, or else it will start to lose mass from its equator due to the “centrifugal” force. Estimate this period.

I seek some links for pointers to be able to answer the question .. "Given that neutrons can approach each other easier than protons, and that the Strong Force will hold neutrons to neutrons when they get within the (short!) range where the Strong Force can be effective, why do we not have pure...

If anyone can help me with this question I'd be greatly appreciative... Here's what I think I understand: Nuclear fission is the breaking of an atomic core of an atom. Like with U-235. It absorbs a slow moving neutron which yields the unstable U-236. Because of the instability the atomic...

can someone Explain the NS-NS or NS-BH or BH-BH mergers proposed to explain short GRB’s. Thanks

Problem Given that \frac{2ma^2 |V|}{\hbar^2} = \left(\frac{7\pi}{4}\right)^2 for an electron in a potential well of depth |V| and width 2a = 10^{-7} \text{cm}, if a 100\text{-keV} neutron is scattered by such a system, calculate the possible decrements in energy that the neutron may...

I want to know more about the cross sections in reaction neutron + targets which neutron has energy in the resonance of target. Help me!

An isolated neutron, changes to a proton within 15 minutes by one of the down quarks becoming an up quark. Why does the change need to include the intermediate step of the heavy W boson? Where did all the W boson mass come from and where did it go? jal

You can calculate that the proton and neutron in a deuteron spend quite some time so far away from each other, that they are outside each others force range. Why doesn't the deuteron break up? Is it because of the binding energy?

well, that's the heading of a project i am doing...i need some help on neutron detectors... how they are dectected and what is the probable graph of count rate vs, pulse height that i might get for a nuclar fission reaction of U-235... can anyone help?

Hey! What would happen if you were orbiting a neutron star and shot a powerful laserbeam at the surface, at some angle? Would it reflect? Would it be absorbed? Thinking (if you picture the star as a perfect neutron star) that the surface is absolutley smooth, it would reflect light...

We all know that the magnetic moment is (gq/2m)J, so then why does a neutron precess in a magnetic field if q=0? This should cause the Hamiltonian to be 0.

It seems strange that a neutron wouldn't have a function within an atom other than obtain mass, a neutral charge, and stick to protons. Do neutrons have more gravity than protons?

If a proton and neutron have a mass of roughly 1.67e-27 kg . And a proton has a diameter of 1.65e-15 .. Is the diameter of a neutron the same?

Homework Statement A neutron star has a mass of 2.0 x 1030 and a radius of 5.0 x 103. Suppose an object falls from rest near the surface of the star. How fast would it be moving after it had fallen a distance of 0.010 m? (Assume that the gravitational force is constant over the distance of the...

Can somebody please explain effective neutron multiplication factor, with example? So when k=1, k>1, k<1 , please give me some example. k=\frac{N_2}{N_1}=\frac{N_3}{N_2}=...=\frac{N_i}{N_i_-_1}

hi there, friends of physics, could anybody help me? All we know that electrons have 4 quantum numbers that describe them and -as the Pauli exclusion principle said- it can´t exist two electrons with the same quantum numbers. But I have a question, does protons and neutrons have quantum numbers...

Is neutron diffusion, traveling neutrons from the nucleus, to direction outside of the nucleus? In my textbook says that there is neutron diffusion, where there is not nuclear reaction. In that case are neutron bouncing off the nucleus?

Homework Statement The neutron is a particle with zero charge. Nonetheless, it has a nonzero magnetic moment with z-component 9.66 * 10^-27 A*m^2. This can be explained by the internal structure of the neutron. A substantial body of evidence indicates that a neutron is composed of three...

Hey all, I need a help to determine the Mass-Radius relationship for a neutron star. I've done it for a white dwarf, but for a neutron star I need to know the Neutron degeneracy pressure expression, can anyone please help me to solve it? I am thinking that if I have the n.deg.pressure...

Anybody have good values and a source for thermal neutron capture cross section for Ba-133, both ground and excited states? CRC Handbook gives 4 barns, but wanted to verify it. Thanks.

Does anybody in PF-land use neutron moisture meters - the ones with Am-241/Be sources that probe into holes in the ground? If so, do you have a regime for regular wipe testing and leak testing? I am interested to find out if there are any cases of a wipe test result that showed contamination...

Is there a simple-model equation for the radial density of a neutron star, from core to shell? I assume there have been models of fermionic gases, anyone have something onhand Is it a specific distribution? Linear? 1/r^2? I know its just a balancing of gravitational potential with strong...

I could not find much info on neutron degenerate matter. Only in reference to neutron stars. http://en.wikipedia.org/wiki/Degenerate_matter neutron degenerate matter Has anyone looked at the possible properties of a neuton liquid or solid to determine if it could act as dark matter? jal

Not sure where to put this post, care more about what's happening on atomic scaI le so i put it here. I am currently taking Heat transfer for engineers and we were discussing the mechanicals for heat transfer, conduction, convection, raditation. In class my professor said that conduction is...

The words neutron degeneracy pressure and electron degeneracy pressure are thrown around a lot when talk of white dwarfs, neutron stars, and black holes comes up. Despite this, I can't find a quantitative description of these critical pressures ANYWHERE. It is almost always described in terms of...

The Chandrasekhar limit (~1.4 Msolar) is an upper limit to the mass a white dwarf star. So this means we can not have a white dwarf star in nature that weighs more than this. But is it true that we can have a neutron star that weighs less than 1.4 Msolar? If so, this makes no sense to me...

Neutron Reaction? Now, I am doing a research about neutron reaction with many level of energy. With intermediate and high energy, I use optical model to calculate the total cross section of the reaction. But in the low energy, I can not do like that because I do not know about the parameters of...

Suppose the neutron decay time n was 89 sec. AND the difference in rest mass between neutron to proton, Qn, was 0.129 MeV. What would the maximum Helium fraction, Yp, be?

Homework Statement "During most of its lifetime, a star maintains an equilibrium size in which the inward force of gravity on each atom is balanced by an outward pressure force due to the heat of the nuclear reactions in the core. But after all the hydrogen "fuel" is consumed by nuclear...

Why is the nn-pair unbound? I don't seem to find the answer in any of my textbooks =/

Homework Statement Neutron stars, such as the one at the center of the Crab Nebula, have about the same mass as our sun but a much smaller diameter. If you weigh 675 N on the earth, what would be your weight on the surface of a neutron star that has the same mass as our sun and a diameter...

I'm writing a paper on Thorium utilization in nuclear reactors. In this connection I'm looking for figures which describe the neutron capture and neutron fission cross sections over a wide energy range (not only thermal). There are probably some online resources unbeknown to me, any hints?

I've looked around and not found any good sources on the gamma energies from fast neutron activation. I need to find the characteristic gamma rays for an MCNP project and currently, I'm relying on energies I get from running some simple cases I set up for the element of interest. Does anyone...

What happens to the neutron? :smile:

It never occurred to me until now why instead of using two charged protons to fuse together, rather fuse neutrons to a hydrogen nucleus. Yes, it seems like cheating the system and therefore that's why I've not heard about this before, but what is the exact mechanism that prevents this from...

It's part of my homework to find an analytical solution to a slab reactor with a reflector. The setup of the core is two slabs of equal thickness (-a to 0 and another 0 to +a) but different values for the diffusion coefficent, macroscopic absorption cross sections, and \nu \Sigma_f. There is a...

At a macroscopic level it appears that when two objects collide, they physically interact and the atoms touch. However the charges of the electrons actually repel one another and they don't physically touch. Correct? A neutron however has no charge so what happens when a neutron collides with...

Hey! I have a question, whose answer I was unable to get after reading some articles regarding neutron start. I've understood that neutron stars lose their rotational energy and emit fragments of it to earth, thus slowing down through the years. I know that this process takes billions of...